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Traits and Lists

Traits and Lists

Learn about traits used in place of interfaces and lists in Scala.

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Traits as Mixins

Scala does not have interfaces. But it has Traits instead, which is somewhat like a combined Interface and Abstract-base-class in Java. However, unlike anything in Java, Traits can be applied to classes or instances of classes and multiple Traits can be used.

Here’s an example using a Trait:

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class SpaceShuttle(val name:String) {
  def launch = println(name + " Take off!")
}
trait MoonLander {
  def land = println("Landing!")
}
class MoonShuttle(name:String) extends SpaceShuttle(name) with MoonLander {
}
val apollo = new MoonShuttle("Apollo 27")
apollo.launch
apollo.land

A class can “extend” any ...